The objective of the clinical core is to provide clinical and laboratory support for each project. This support will include provision of blood and endometrial biopsy specimens from patients attending an inner-city public health clinic dedicated to the evaluation and treatment of STDs. In addition, the core will perform chlamydial cultures and serologies in support of Projects 2-4. It also will perform blastogenic assays on peripheral blood lymphocytes in support of Project 2, and will purify elementary bodies and chlamydial major outer membrane protein for use in these and other assays.